Three defects which have been observed with aging are increased vascular stiffness, depressed responsiveness to catecholamines, and depressed cardiac function. Derangements in adrenergic signaling may presage dysfunction in the cardiac and vascular systems that is induced by the aging process. There are three major components to this study: 1) that altered adrenergic control of vasoactivity precedes increased stiffness in the aged vasculature; 2) that altered adrenergic control of left ventricular (LV) function presages the decline in LV function in the aged heart; and 3) that changes in cardiac and vascular structure in the aging heart are responsible for altered vascular and LV function, but these changes are not necessary for altered adrenergic signaling. To address these components the alterations in arterial pressure/dimension relations, LV function and altered adrenergic signaling with aging will be determined in conscious, chronically instrumented monkeys. The alterations in aging at the cellular and molecular level and histologic alterations in cardiac and vascular structure will be examined. These studies will be conducted in 4 groups of monkeys: 1) younger adults (3-5 years); 2) mature adults (7-10 years); 3) older adults (15-19 years); and 4) senescent adults (older that 20 years).